Method of making plasterboard



comPoslflows, COATING, ORHPLASTIC. Cross Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE METHOD OF MAKING PLASTERBOARD Hans O. Kaufimann and Dean D. Crandell, Buffalo, N. Y., assignors to Bufialo Electra-Chemical Company, 1110., Buffalo, N. Y.

No Drawing.

28 Claims.

This invention relates to building products and their method of manufacture and more particularly to such produris containing minute pores or vesicles incorporated artificially therein.

Heretofore, it has been proposed to prepare 'porous building materials from cementitious material, such as stucco, by liberating gases such as hydrogen or carbon dioxide by chemical reaction, but the products so produced possess the disadvantage of irregularity of pore structure and non-homogeneity inducing weakness in the product which weakness is accentuated by the introduction of substantially large quantities of non-cementitious or non-hardening chemicals. It has also been proposed to use hydrogen peroxide as a source of the gaseous materials producing the vesicles in the material by liberating oxygen from a peroxide by employing organic materials as catalytic agents.

Many products used for building purposes, if made of stucco or plaster only, are brittle and frangible and possess certain characteristics which render them undesirable as construction materials and consequently fibrous materials are ordinarily incorporated with stucco or plaster to 3x119, when such peroxide is addedt'o Application January 2'7, 1933, Serial No. 653,929

ratus, and of a suitable consistency. A suitable pulp can be prepared from 2500 gallons of water and from about one and a half to two an a alf percent of dry fiber material, as for instance, 500 pounds of dr aper fiber, although either larger or smaller quantities may be incorporated in the beater depending upon the consistency or cream of the finished pulp desired and the properties required in the final building article.

In the manufacture of porous material in which pulp is incorporated with stucco or plaster, it has been found preferable, in accordance with our invention, to incorporate the oxygen have the pulp ready at hand for mixture with Examiner stucco, since the time between the initial wet-,-

ting of the stucco and the period at which the stucco or plaster or other cementitious material sets or crystallizes, is circumscribed as to time. In so preparing the fibrous pulp and water cream the bath possesses the power of inducing decomposition of peroxide, such n I decrease the frangibility of the set plaster and Wife? mixture, and either substantial quantities render the final article more flexible and induce a resiliency therein not possessed by the set plaster alone. When attempts are made to prepare porous particles containing a fibrous filler much peroxide is lost by decomposition. The present invention obviates this defect as will presently become apparent.

The present invention provides a method for the manufacture of porous building materials such as wall board from cementitious mixes wherein fibrous substances have been incorporated to improve the properties of the set material; produce a vesicular building product characterized by minute and uniformly distributed vacuoles; and to provide a method for the manufacture of a porous product possessing uniform strength. The invention further provides a method of preparing a fibrous pulp for use as a filler in the manufacture of porous building material having incorporated uniformly therewith a gas liberating substance, relatively stable at the conditions specified and that can be prepared and stored prior to its use without premature decomposition of the gas liberating constituent.

In the manufacture of our improved building product, a pulp of fiber, such as a er fiber.

and the like is prepared in a con of such added hydrogen peroxide are decomposed and the oxygen normally available therefrom, lost as an effective agent for producing vesicles in the final product, or the entire action of the hydrogen peroxide is lost prior to the admixture of the pulp with the plaster. By incorporating an acid, an acid inducing or acid producing mm the pulp in predetermined amounts the hydrogen peroxide can be rendered substantially stablefa'fidtli'e'pulp'ahd proTide mixture grease ainsavggiggg'g g in large batflifiwlthdfitjdecdfipo sition of substanti'al'amdlfpf peroxide r pe ds er a weeli of'tenl day s. ln actual ownersh p-rea ticjhow'ever, it has been found more profitable to prepare the pulp and peroxide mixture about 8 hours in advance of the use of the pulp.

As acid inducing or acid producing materials,

mineral acids such as h drochloric or $111 huric acid, may be added in quantlties suficient to produce a hydrogen ion concentration of be- The amount of h dro en eroxide incorporated in a 2500 gallon mix is aEout 72 /0 of hun-r dred volume peroxide, that is about 12.5 gallons as sodium hosphag alum, and other acid and HyHrolyzaBle sa s.

of peroxide, although this quantity is illustrative only and the amount may be varied considerably from this figure depending upon the number and size of the vesicles desired in the 5 resultant building materials and the properties and use to which the material is to be put.

It is to be noted that in characteristic mixtures of pulp predetermined quantities of starches, dextrine, glues, etc., are added in order ac as a on lng an sizing material and to produce characteristic properties when the pulp is used to produce plaster wall board.

In order to induce uniformity of evolution of oxygen from the hydrogen peroxide and produce an even distribution of gas pores in the finished building material, a latent catalytic agent is incorporated and distributed in the pulp which possesses a potential peroxide decomposing action. To this end, certain water soluble metallic salts capable of being changed to an oxide or hydrated oxide form by the addition of suitable water soluble alkalis and soluble in the liquid of the mix to produce positive peroxide decomposing agents which are colloidal or semi-colloidal in form and which therefore form or present loci or nuclei at which decomposition of the hydrogen peroxide occurs with evolution of oxygen and production of water, are mixed with the pulp prior to its incorporation with plaster i. e. a cementitious material capable of setting or hardening upon the addition of water thereto. As all of these materials are intimately distributed and mixed with the fiber or paper pulp, uniform evolution of oxygen from the peroxide is induced with the formation of a uniform distribution of substantially uniformly sized gas particles forming the pores or vesicles in the finished wall board or building material. As latent catalytic agents, ls of man a oer iron cobl and the ie, may be used as these salts prouce hydroxides or hydrated oxides in water when water soluble alkalis are added thereto. The amount of such material added is small in quantity and is not suflicient to affect adversely the physical properties of the plaster pulp mass as the only by-product of the decomposition of hydrogen peroxide is water which may be readily evaporated or dried out from the finished wall board. As illustrative of the amount of peroxide decomposing agent required, it may be mentioned that 100 milligrams of man anous chloride per 3000 grams of plaster 5m efficient and desirablecon centration although somewhat larger quantities of the catalysts may be employed.

After the preparation of the fiber pulp mixture and'incorporation therein of the starches, glues, potential catalytic agent, and peroxide, the fiber pulp is fed into a pulp feeder and distributed with the desired quantity of stucco, calcined gypsum or plaster upon an endless belt in the well known manner and permitted to soak for a short time and thereafter agitated or stirred and then dropped into a mixer.

The mix of fiber pulp and plaster is made alkaline by the addition of ustic soda otash or other alkali to neutralize the am 1 of the pulp and maintain the hydrogen ion concentration of the total mix to a pH of about 7.5 to 11.0. This point may be determined by the use of an indicator such as phenolphthalein or other well known hydrogen ion indicator. Upon addition of the water soluble alkali the latent catalytic agent is activated and changed from a potential hydrogen peroxide decomposing agent to an active hydrogen peroxide decomposing agent and bubbles of gaseous oxygen are formed uniformly throughout the mix. These bubbles of oxygen do not escape from the plastic mass but are retained and inclosed therein during the set- 5 ting or crystallizing stage of the cementitious material and produce the pores or vesicles which are characteristic of the finished product.

In the preparation of wall board the slightly alkaline mix is fed from the mixer onto an endless belt in the well known manner and by means of a press roll and gravity belt the proper caliper of the board is obtained prior to the introduction of the board into the drying kiln. When it is desired to encase the fibrous wall board in upper and lower finished paper covers, the mix is fed upon a lower paper sheet carried by the endless belt, and an upper paper sheet is rolled upon the mix, adherence of the paper to the mix being obtained by the natural adhesion of crystallizing gypsum to paper surface plus, when desired, the use of adhesives in the mix such as starch glue, dextrine, um arabic and the like. maimed 1's:'

1. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a potentially active hydrogen peroxide decomposing agent to the pulp and distributing it therewith, and adding a predetermined quantity of a peroxide to the bath while maintaining the acidity of the bath within a range where no substantial evolution of oxygen from the peroxide occurs.

2. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a potentially active hydrogen peroxide decomposing agent to the pulp and distributing it therewith, and adding a predetermined quantity of a peroxide to the bath while maintaining the acidity of the bath within a range where the peroxide decomposing agent remains substantially inactive.

3. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a manganese salt to the pulp and distributing it therewith, and adding a predetermined quantity of hydrogen peroxide to the bath while maintaining the acidity of the bath within a range where no substantial decomposition of the peroxide occurs.

4. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a cobalt salt to the pulp and distributing it therewith, and adding a predetermined quantity of hydrogen peroxide to the bath while maintaining the acidity of the bath within a range where no substantial decomposition of the peroxide occurs. 70

5. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predeter- 7 106. COMPOSITIONS,

COATING 0R PLASTIC.

mined quantity of a peroxide to the pulp while maintaining the acidity of the bath between about pH 3.5 to pH 6.

6. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a copper salt to the pulp and distributing it therewith, and adding a predetermined quantity of hydrogen peroxide to the bath while maintaining the acidity of the bath within a range where no substantial decomposition of the peroxide occurs.

7. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a potentially active peroxide decomposing agent to the pulp and distributing it therewith, distributing a predetermined quantity of a peroxide. in the bath, and mixing a sufficient quantity of acidulous material with the bath to prevent substantial evolution of oxygen from the peroxide.

8. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a potentially active peroxide decomposing agent to the pulp and distributing it therewith, distributing a predetermined quantity of a peroxide in the bath, and mixing a sufficient quantity of a hydrolyzable salt with the bath to prevent substantial decomposition of the peroxide.

9. The process of preparing fibrous material for use in the manufacture of porous building material which comprises beating a quantity of fibrous material with a liquid chemically inert to the fiber to form a pulp, adding a predetermined quantity of a potentially active peroxide decomposing agent to the pulp and distributing it therewith, distributing a predetermined quantity of alum with the bath to maintain a desirable acidity therein and to cause the peroxide decomposing agent to remain substantially inactive.

10. The method of manufacturing porous building material which comprises mixing a fibrous pulp containing a potentially active peroxide decomposing agent and a peroxide, with a cementitious material and rendering the peroxide decomposing agent active.

11. The method of manufacturing porous building material which comprises mixing a fibrous pulp of a predetermined acidity and containing a potentially active peroxide decomposing agent and hydrogen peroxide, with a cementitious material and changing the acid concentration to render the peroxide decomposing agent active.

12. The method of manufacturing porous building material which comprises mixing a fibrous pulp containing a potentially active peroxide decomposing agent and hydrogen peroxide, with a cementitious material and thereafter adding an alkali to the mixed pulp and cementitious material to render the hydrogen peroxide decomposing agent active.

13. The method of manufacturing porous building material which comprises mixing a fibrous pulp containing a potentially active peroxide decomposing agent and hydrogen peroxide, with a cementitious material and thereafter adding suificient alkali to the mixed pulp and cementitious material to produce an alkalinity of between about pH 7 to 11.

14. The method of manufacturing porous building material which comprises mixing a fibrous pulp containing a quantity of a manganese salt and hydrogen peroxide, with a cementitious mix and thereafter adding sufficient alkali to the mixture of pulp and cementitious material to change the manganese salt to the hydrated oxide form whereby the manganese salt is rendered active as a peroxide decomposing agent and oxygen evolved uniformly throughout the mix, the oxygen remaining in the mixture during and after the period required for the mixture to set.

15. The method of manufacturing porous wall board which comprises mixing an aqueous fibrous pulp containing a predetermined quantity of a manganese salt and hydrogen peroxide with plaster, adding sufiicient alkali to the mixture of pulp and plaster to change the manganese salt to the hydrated oxide form and thereafter permitting the mixture to set.

16. The method of manufacturing porous wall board which comprises mixing a fibrous pulp containing a predetermined quantity of a cobalt salt and hydrogen peroxide with a water and plaster mix, mixing suflicient alkali with the mixture of pulp and plaster to change the cobalt salt to the hydrated oxide form and thereafter permitting the mixture to set.

17. The method of manufacturing porous wall board which comprises mixing a fibrous pulp containing a predetermined quantity of a copper salt and hydrogen peroxide with a water and plaster mix, mixing suificient alkali with the mixture of pulp and plaster to change the cobalt salt to the hydrated oxide form and thereafter permitting the mixture to set.

18. The method of manufacturing wall board which comprises mixing an acid paper pulp containing a predetermined quantity of a manganese salt and hydrogen peroxide with plaster, mixing suflicient alkali with the mixture of pulp and plaster to change the alkalinity of the resultant mix to a pH of about pH 7 to 11, and thereafter permitting the mixture to set.

19. The process of manufacturing porous wall board which comprises preparing a pulp from fibrous material and water, adding hydrogen peroxide to said pulp, incorporating a potential hydrogen peroxide decomposing agent to said pulp, mixing said pulp with a cementitious material'capable of setting upon the addition of water thereto, adding a material to the mixture of pulp and cementitious material capable of rendering the potential agent active whereby oxygen is evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet, and impressing an upper fibrous sheet thereon.

20. The process of manufacturing porous wall board which comprises preparing a pulp from fibrous material and water, adding hydrogen peroxide to said pulp, incorporating a potential hydrogen peroxide decomposing agent to said pulp, mixing said pulp with calcined gypsum, adding a material to the mixture of pulp and calcined gypsum capable of rendering the potential agent active whereby oxygen is evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet and impressing an upper fibrous sheet thereon.

Examiner 21. The process of manufacturing porous wall board-which comprises preparing a pulp from fibrous material and water, adding hydrogen peroxide to said pulp, incorporating a potential hydrogen peroxide decomposing agent to said pulp, mixing said pulp with a cementitious material capable of setting upon the addition of water thereto, adding a material to the mixture of pulp and cementitious material capable of rendering the potential agent active whereby oxygen is evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet, and impressing an upper fibrous sheet thereon before the mixture sets.

22. The process of manufacturing porous wall board which comprises preparing a pulp from fibrous material and water, adding hydrogen peroxide to said pulp, incorporating a potential hydrogen peroxide decomposing agent in said pulp, mixing said pulp with calcined gypsum, adding a material to the mixture of pulp and calcined gypsum capable of rendering the potential agent active whereby oxygen is evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet and impressing an upper fibrous sheet thereon before the mixture sets.

23. The process of manufacturing porous wall board which comprises preparing a pulp from fibrous material and water, adding hydrogen peroxide to said pulp, incorporating a water soluble salt of a metal in said pulp capable of forming a colloidal hydroxide, mixing said pulp with calcined gypsum, adding an alkali to the mix of pulp and calcined gypsum whereby a colloidal hydroxide of said metal is formed and oxygen evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet, and impressing an upper fibrous sheet thereon.

24. The process of manufacturing porous wall board which comprises preparing a pulp from fibrous material and water, adding hydrogen a Ila-1:2;

peroxide to said pulp, incorporating a water soluble salt of a metal in said pulp capable of forming a colloidal hydroxide, mixing said pulp with a cementitious material capable of setting upon the addition of water thereto, adding an alkali to the mix of pulp and cementitious material whereby a colloidal hydroxide of said metal is formed and oxygen evolved from the hydrogen peroxide, molding said mixture upon a lower fibrous sheet, and impressing an upper fibrous sheet thereon.

25. The method of manufacturing porous building material from a cementitious material, an aqueous fiber pulp containing a potentially active peroxide decomposing agent, and a peroxide which comprises mixing the fiber, peroxide and' cementitious material and thereafter adding suflicient alkali to the mixture to render the same alkaline.

26. The method of manufacturing porous building material from a cementitious material, an acidulous aqueous fiber pulp containing a potentially active peroxide decomposing agent, and a peroxide which comprises mixing the fiber, peroxide and cementitious material, and thereafter adding sufiicient alkali to the mixture to render the same alkaline.

27. The method of manufacturing porous building material from plaster, an aqueous fiber pulp and hydrogen peroxide which comprises mixing the fibers, hydrogen peroxide and plaster, and thereafter adding suflicient alkali to the mixture to render the same alkaline.

28. The method of manufacturing porous building material which comprises mixing calcined gypsum, fiber pulp, hydrogen peroxide, water and a potentially active peroxide decomposing agent and thereafter adding an alkali to the mixture.

HANS O. KAUFFMANN. DEAN D. CRANDELL. 

